The present invention relates to multi-bit to pulse width modulated signal conversion, with extensions to digital-to-analog conversion. In particular, it has application to conversion of pulse code modulated signals, such as used in CDs and DVDs, to audio output.
Many streaming media formats produce a multi-bit data stream. For instance, audio CDs typically encode music as a 16-bit pulse code modulated signal. MP3 files also may be decoded as pulse code modulated signals.
Audio fidelity depends in part on the signal to noise ratio (SNR) of the digital-to-analog (D/A) converter used. This converter may be part of a CD player, located on a sound card or included with powered speakers that are digitally driven. Manufacturers compete on the basis of the SNR achieved by their equipment. For instance, Creative Labs currently (in September 2005) advertises the Audigy Pro 4 sound card as achieving an SNR of 113 decibels in some modes.
An additional consideration in D/A conversion, or in any digital design, is simplicity. The fewer gates required to produce a high fidelity decoder, the better. Accordingly, an opportunity arises for new digital designs, especially digital designs that achieve strong signal-to-noise ratios.